1. Field of the Invention
The present invention relates to an endoscope apparatus that generates an endoscopic image by using illuminating lights of a plurality of wavelength bands.
2. Description of the Related Art
Conventionally, in a medical field, various kinds of low-invasive examinations and surgical operations using endoscopes have been performed. A surgeon inserts an endoscope into a body cavity, observes an object an image of which is picked up by an image pickup apparatus provided at a distal end portion of an endoscope insertion portion, and can perform treatment to a lesion part by using a treatment instrument inserted through an inside of a treatment instrument channel in accordance with necessity. A surgical operation using an endoscope does not carry out a laparotomy or the like, and therefore has the merit of putting less physical burden on a patient.
Further, some of endoscope apparatuses are capable of performing not only normal observation using a white color light but also capable of performing special light observation using a special light such as an infrared light in order to observe internal blood vessels.
For example, Japanese Patent Application Laid-Open Publication No. 2011-92690 as a first conventional example, discloses R, G and B filters that partially overlap one another in FIG. 3 in the Publication, and respectively transmit lights of different wavelength bands, and details of generating a first to a third narrow band image pickup signals by sequentially turning on and causing a first to a third narrow band light sources to emit a first to a third narrow band lights. A third narrow band light N3 is a narrow band light in overlapping wavelength bands in the G and B filters.
Further, Japanese Patent Application Laid-Open Publication No. 2010-193421 as a second conventional example discloses R, G and B filters having such transmittances that include wavelength bands partially overlapping one another, and details of simultaneously emitting special lights 1, 2 and 3 respectively having different light emission wavelength bands (paragraph [0064] in the publication), and details of selectively emitting the special lights 1, 2 and 3 (paragraph [0068] in the publication).